Known radio systems, such as WLAN (WLAN: Wireless Local Area Network) according to the IEEE 802.11 standard and Bluetooth according to the IEEE 802.15.1 standard that permit a transparent transmission of Ethernet-based communications protocols, transmit these protocols in a highly inefficient way, because the Ethernet protocol is normally packed into a radio data packet without further optimization. Because the Ethernet packets according to the IEEE 802.3 standard must be composed of at least 64 bytes, but many automation systems transmit only a few usable data bytes in an Ethernet data frame, the ratio of usable data to protocol overhead or to the total protocol length is not favorable in Ethernet systems. This is made even worse in radio transmission, because a radio connection has a data rate even lower than that of an Ethernet system. In addition, the radio connection requires the addition of protocol overhead required for the communications, wherein transmission is further possible only in a half-duplex method. Therefore, the cycle time response of a radio-based Ethernet system is basically more disadvantageous than the time response of a wired Ethernet system such as the Profinet system.
In known radio systems, it is problematic that often only a statistical medium access is permitted. This method produces disadvantages in the time response of an automation solution through, for example, increased jitter in the communications cycles. For optimizing the time response, for example, polling-based medium access methods can be used that are standard for Bluetooth and that are approved for WLAN. Indeed, even in these systems, for each polling cycle only one data packet of an I/O subscriber is transmitted. However, if there are several I/O subscribers behind a radio connection, wherein these subscribers communicate cyclically with a controller, for example, in a permanently installed network part, then the time response of the total communications between the I/O subscribers is not always predictable. For example, in the case of the Profinet standard, more than one I/O subscriber cannot be provided behind the radio bridge in a WLAN transmission.